Many methods are implemented in industry for controlling production/distribution lines, not only for detecting problems arising on transport paths but also reliably determining a quantity of items produced or distributed on said lines. Particularly, some of these methods are used for ensuring proper dispatching or packaging of said items, or even further allowing accurate billing or tax accounting of the items so produced or distributed.
Imaging devices are of common use for controlling production of items on automated production lines. For example, on bottling lines, strobe light (using a LED lighting unit controlled by a laser trigger device which detects the presence of an item, for example) illuminates bottles transported in single file on a conveyor and marked with a barcode (1D or 2D barcode, like SKU code or data matrix, for example), and digital cameras take digital images of the so illuminated bottles. A strobe light source typically uses a LED lighting unit controlled by a laser trigger device, which detects the presence of an item. Conventional image processors automatically detect on a digital image of an item a region of interest containing a barcode pattern and then identify the item by decoding the detected barcode. Such identification may be used, for example, for correctly labeling the above bottles according to their type (or content, etc.). There are many known techniques relating to image processing which can be used for identifying an item marked with an identifier (including item identification data) from a digital image of said identifier.
The above imaging devices, or readers, may be adapted to read identifiers from light reflected or emitted by said identifier within any optical wavelength range between the UV (ultraviolet) and the IR (infrared).
There are also many other well known techniques adapted to different types of identifiers. For example, an RFID reader is adapted for reading identifiers like RFID tags disposed on items, these RFID tags including item identification data (possibly encrypted). As another non-limiting example, the identifier may be a magnetic marking, and the corresponding adapted reader is then of magnetic sensor type.
Thus, whatever specific type of identifier including identification data is used for marking items transported on a production/distribution line, an adapted type of reader is used for reading said identifier and sending a corresponding reader signal to a controller having a processor capable of extracting identification data from said reader signal.
Items on a conventional production/distribution line are transported (for example, on a conveyor) arranged in single file, each transported item being marked with a unique item identifier including unique item identification data of the item, the items are then successively collected by a collector device (like a pusher, for example) to form a batch of a given number N of said items. Such a batch of items is then packaged by a packaging device, and a corresponding packed batch is delivered. The collector device generally includes a sensor operable to detect that a batch of N items has been formed (for example, a mechanical counter, or an electronic counter in which a light beam between diodes is interrupted by a transported item). This sensor is operable to deliver a batch signal each time a batch of N items has been counted.
Operations on the line are generally controlled by a controller. Also, mounted on the line, at the level of a reading zone, a reader connected to the controller typically reads the unique identifier on each one of the items in single file within said reading zone, and sends corresponding successive reader signals to the controller. The controller has a processor programmed to extract each unique item identification data from the received reader signals. The processor may in fact be split, for example, between the controller itself and the reader (i.e. some processing steps of the reader signal being then executed at the reader), or may even involve a remote connected processing unit.
As an example, the reader classically comprises a camera (or a plurality of cameras around the reading zone, and possibly including illumination source for illuminating the items to be imaged) set for reading a barcode on one item at a time as the items in single file are transported through the reading zone, by taking a digital image of a region of interest containing the barcode on the (illuminated) item. Many known methods are available to be implemented by the processor for detecting and decoding the digital image of the barcode sent by the reader.
However, due to quite frequent jams on the line causing loss or deterioration of items, or even due to fraudulent interception of items along the transport path between the reading zone and the collector device, it is not sure that all the items identified by the reader in fact correspond to the items counted at the level of the collector device's sensor. Thus, problems are generated in case items having being identified on the line (and thus, possibly accounted for taxation, or billed as being delivered) are lost before being collected by the collector device, or in case the collected batches of items in fact contain unidentified items and are nevertheless distributed, or packaged by the packaging device.
Moreover, the above problems are even made worse in case the items must be transported in groups along the transport path.
Consequently, the above conventional controlling of operations is not well adapted to real-time item identification, particularly on high speed production or distribution lines, and especially if the items are transported grouped along the transport path and that every single item passing on the line needs to be identified.